MPC7448 datasheet(6/60 Pages) FREESCALE

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MPC7448 RISC Microprocessor Hardware Specifications, Rev. 4

Freescale Semiconductor

Features

•

Efficient data flow

— Although the VR/LSU interface is 128 bits, the L1/L2 bus interface allows up to 256 bits.

— The L1 data cache is fully pipelined to provide 128 bits/cycle to or from the VRs.

— The L2 cache is fully pipelined to provide 32 bytes per clock every other cycle to the L1 caches.

— As many as 16 out-of-order transactions can be present on the MPX bus.

— Store merging for multiple store misses to the same line. Only coherency action taken

(address-only) for store misses merged to all 32 bytes of a cache block (no data tenure needed).

— Three-entry finished store queue and five-entry completed store queue between the LSU and

the L1 data cache

— Separate additional queues for efficient buffering of outbound data (such as castouts and

write-through stores) from the L1 data cache and L2 cache

•

Multiprocessing support features include the following:

— Hardware-enforced, MESI cache coherency protocols for data cache

— Load/store with reservation instruction pair for atomic memory references, semaphores, and

other multiprocessor operations

•

Power and thermal management

— Dynamic frequency switching (DFS) feature allows processor core frequency to be halved or

quartered through software to reduce power consumption.

— The following three power-saving modes are available to the system:

– Nap—Instruction fetching is halted. Only the clocks for the time base, decrementer, and

JTAG logic remain running. The part goes into the doze state to snoop memory operations

on the bus and then back to nap using a QREQ/QACK processor-system handshake

protocol.

– Sleep—Power consumption is further reduced by disabling bus snooping, leaving only the

PLL in a locked and running state. All internal functional units are disabled.

– Deep sleep—When the part is in the sleep state, the system can disable the PLL. The system

can then disable the SYSCLK source for greater system power savings. Power-on reset

procedures for restarting and relocking the PLL must be followed upon exiting the deep

sleep state.

— Instruction cache throttling provides control of instruction fetching to limit device temperature.

— A new temperature diode that can determine the temperature of the microprocessor

•

Performance monitor can be used to help debug system designs and improve software efficiency.

•

In-system testability and debugging features through JTAG boundary-scan capability

•

Testability

— LSSD scan design

— IEEE Std. 1149.1™ JTAG interface

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